The center for Environmental Health Sciences has become the focal point at MIT for teaching and research regarding the sources, movement and effects on human health of the chemicals in the human environment. The Center's research programs in source studies began more than twenty years ago with studies of food-borne chemicals, such as fungal toxins, plant flavonoids, cooking pyrolysates, nitrosamines and the constituents of food-smoking preparations. For the past ten years we have studied the chemistry of fossil fuel combustion in terms of the formation of mutagenic and carcinogenic effluents. We continue to use our ability to analyze the chemistry and biological effects of complex mixtures and have initiated a new program to characterize means, such as incineration and wet oxidation, to destroy toxic wastes in a safe and efficacious manner. These efforts require the close collaboration of chemical engineers, analytical chemists and toxicologists. This past year the faculty of the Parsons Laboratory for Water Resources and Hydrodynamics has joined our effort. They study processes by which chemicals move through geostrata into groundwater, the absorption of chemical and microbial reactions which transform these chemicals and the ultimate consequences in terms of the kinds and amounts of chemicals actually ingested by humans through drinking water. Together we hope to combine chemical and toxicologic analyses so that priorities for remedial action can be set in terms of biological hazard. Woven through the fabric of our Center is the work of toxicologists, geneticists and cell biologists who are devising means to directly measure the kinds and amounts of chemicals actually reacting with human proteins and DNA, to diagnose which of these chemicals actually cause genetic change by measuring mutational spectra in humans and to identify which of the numerous human protooncogenes are actually at significant risk of genetic transformation via the action of environmental chemical exposure. Our collective goal is to develop the tools to directly assess the nature and causes of disease in humans of genetic origin among which we list germinal mutations and mutations leading to the clonal somatic diseases, such as atherosclerosis and cancer.